Abstract
A multi-stage compressor for compressing a fluid, the compressor comprising two or more cylinders each having a compression chamber and a piston, so that a fluid in each of the compression chambers can be com-pressed by the associated piston; the cylinders being connected in series such that a fluid entering an inlet of the compressor can be compressed to a first pressure in the compression chamber of a first cylinder and, then, enter into the compression chamber of a second cylinder where the compressed fluid is compressed to a second higher pressure and, before the fluid exits from an outlet of the com-pressor; wherein each piston is driven by one and the same crankpin of the compressor. Furthermore, a method for compressing a fluid, and a system for comprising the multi-stage stage compressor are disclosed.
Claims
1-55. (canceled)
56. A multi-stage compressor for compressing a fluid, the compressor comprising: two or more cylinders, each cylinder having a compression chamber and a piston, so that a fluid in each of the compression chambers can be compressed by the associated piston; the cylinders being connected in series such that a fluid entering an inlet of the compressor can be compressed to a first pressure in the compression chamber of a first cylinder, and, then enter into the compression chamber of a second cylinder where the compressed fluid is compressed to a second higher pressure before the fluid exits from an outlet of the compressor; wherein each piston is driven by one and the same crankpin of the compressor.
57. A multi-stage compressor according to claim 56, further comprising at least one supply compressor for supplying compressed fluid at a pressure above atmospheric pressure to the compression chamber of the first cylinder, wherein the supply compressor and the pistons is driven by one and the same crankshaft as the pistons of the multi-stage compressor.
58. A multi-stage compressor according to claim 57, wherein the at least one supply compressor is driven by the one and same crankpin as the pistons of the multi-stage compressor.
59. A multi-stage compressor according to claim 56, wherein a separate and individual sliding shoe for engaging with the crankpin is attached to a bottom end of each piston.
60. A multi-stage compressor according to claim 56, wherein a housing of the multi-stage compressor comprises at least one guide groove, the at least one guide groove being configured for guiding the movement of at least one guide element attached to a piston.
61. A multi-stage compressor according to claim 56, wherein the multi-stage compressor comprises at least one linear bearing configured for guiding the movement of an associated piston of the pistons of the multi-stage compressor and/or at least one guide element attached to the associated piston.
62. A multi-stage compressor according to claim 56, wherein the compression chamber of at least a first cylinder of the two or more cylinders is connected to the compression chamber of a second cylinder through at least one non-return valve for preventing flow of fluid from the compression chamber of the second cylinder to the compression chamber of the first cylinder.
63. A multi-stage compressor according to claim 62, wherein the at least one non-return valve is located externally of the two or more cylinders inside a valve pipe such that a fluid flowing from the compression chamber of at least a first cylinder to the compression chamber of a second cylinder flows through the valve pipe and the at least one non-return valve.
64. A multi-stage compressor according to claim 63, wherein the valve pipe is removably attached between two cylinders.
65. A multi-stage compressor according to claim 63, wherein the valve pipe extends between a given cylinder and a directly following cylinder.
66. A multi-stage compressor according to claim 56, wherein for at least one cylinder, a cylinder housing comprising the associated compression chamber of the given cylinder is detachable from and attachable to the compressor.
67. A multi-stage compressor according to claim 59, wherein each sliding shoe is secured to the crankpin by an associated separate annular holding ring which encloses a circumference of the crankpin.
68. A multi-stage compressor according to claim 59, wherein at least one sliding shoe comprises a recess or opening for receiving a holding ring.
69. A multi-stage compressor according to claim 56, wherein the compressor is configured such that, in at least one of operation and at standstill, at least one or each piston do(es) substantially not touch an inner wall of the associated compression chamber.
70. A multi-stage compressor according to claim 56, wherein the compressor is configured such that, in operation, at least one piston only or substantially only moves in the radial direction of the compressor.
71. A multi-stage compressor according to claim 56, wherein the first cylinder comprises at least one associated rod seals for sealing against an associated piston of the first cylinder.
72. A multi-stage compressor according to claim 56, wherein at least one of the crankpin and a crankpin bearing provided on the crankpin has an outer diameter that is at least 1.1 times a smallest and/or largest stroke length of each of the pistons.
73. A multi-stage compressor according to claim 56, wherein a length of a lever arm acting on a rotation axis about which the crankpin rotates is equal to or less than 200% of a smallest and/or largest stroke length of each of the pistons.
74. A method for compressing a fluid in a multi-stage compressor, the compressor comprising two or more cylinders, each cylinder having a compression chamber and a piston so that a fluid in each of the compression chambers is compressed by the associated piston, wherein the cylinders are connected in series such that a fluid entering an inlet of the compressor is compressed to a first pressure in the compression chamber of a first cylinder and, then, enters into the compression chamber of a second cylinder where the compressed fluid is compressed to a second higher pressure, and wherein each piston is driven by one and the same crankpin of the compressor.
75. A system for compressing a fluid, the system comprising: a multi-stage compressor according to claim 56 and a second compressor configured to provide fluid at a pressure above atmospheric pressure to the inlet of at least one of the multi-stage compressor and the compression chamber of the first cylinder.
Description
BRIEF DESCRIPTION OF DRAWINGS
[0128] In the following, non-limiting exemplary embodiments will be described in greater detail with reference to the drawings, in which:
[0129] FIG. 1 shows a perspective view of the front side of the assembled multi-stage compressor,
[0130] FIG. 2 shows a perspective view of the rear side of the compressor in FIG. 1,
[0131] FIG. 3 shows a side view of the compressor in FIG. 2,
[0132] FIG. 4 shows a section view along line A-A of the compressor in FIG. 3,
[0133] FIG. 5 shows a partially exploded view of the compressor in FIG. 1,
[0134] FIG. 6 shows an enlarged detail view of the crankpin, piston, and sliding shoe assembly of the compressor in FIG. 5, and
[0135] FIG. 7 shows an exploded view of the crankpin and piston assembly seen in FIG. 6,
[0136] FIG. 8 shows the multi-stage compressor with an alternative embodiment of the cooling pipes and cooling jacket,
[0137] FIG. 9 shows an embodiment of the multi-stage compressor comprising supply compressors,
[0138] FIG. 10 shows a cross-section through the multi-stage compressor in FIG. 10 corresponding to the cross-section shown in FIG. 4,
[0139] FIG. 11 shows a close up of the cross-section of a supply compressor from FIG. 10,
[0140] FIG. 12 shows an alternative piston movement guide,
[0141] FIG. 13 shows a second alternative piston movement guide, and
[0142] FIG. 14 shows a third alternative piston movement guide.
DETAILED DESCRIPTION OF DRAWINGS
[0143] Starting with FIG. 1 a multi-stage compressor 1 according to the present disclosure is seen from the front. The compressor 1 comprises three cylinders 2a, 2b, 2c each with a cylinder housing 22. The cylinders are interconnected by valve pipes 7 which in this embodiment have cooling jackets 71 for cooling the valve pipes 7 attached to them. Extending in parallel to the valve pipes 7 are cooling pipes 26 for cooling the cylinders 2a, 2b, 2c. The cooling pipes 26 connect cooling channels (not shown) in the cylinder housings 22 to allow a flow of cooling medium for cooling the cylinders 2a, 2b, 2c to flow through the compressor 1. The compressor 1 further comprises an inlet 12 for fluid to enter a first cylinder of the compressor 1 and an outlet 13 for exiting a final cylinder of the compressor 1. The fluid supplied to the inlet 12 of the compressor 1 may be pressurized or pre-compressed such that the fluid being compressed in the first cylinder 2a is already pressurized before being compressed in the cylinder. For example the fluid supplied to the inlet may be pressurized to 8 bar as in the present example. The compressor further has a crankshaft 6 which comprises two interconnected separate shafts 61. One of the shafts 61 is configured for being connected to a drive unit for driving the compressor 61 i.e. rotating the crankpin 5 and the other shaft 61 exiting the rear side of the compressor is optionally configured for being connected to and drive a second compressor.
[0144] Moving to FIG. 2 where the compressor 1 is seen from the rear side, the guide elements 33 for guiding the movement of pistons 3 are seen guided in guide grooves 15. As can be seen in FIGS. 1 and 2, the majority of components of the compressor 1 are connected to each other via bolts 16 e.g. the compressor housing 11, cylinder housings 22, inlet 12, outlet 13, and shield plate 17. This allows easy assembly/disassembly as well as maintenance and swapping of components to suit different use cases. In FIG. 3 the compressor 1 is seen from a side, where it can be seen that the two interconnected shafts 61 of the crankshaft 6 are concentric and extend an equal length from the compressor housing 11.
[0145] Moving to FIG. 4 a section view of the compressor 1 along line A-A in FIG. 3, where the sliding shoes have been removed, is shown. Here the compression chambers 21 in the cylinders 2a, 2b, 2c and the associated cylindrical pistons 3 can be seen. The cylinders 2a, 2b, 2c are located about the rotation axis RA and extend in a radial direction away from rotation axis RA. The compression chambers 21 which are located within the cylinders are of different diameters with the associated pistons 3 having a corresponding diameter d i.e. the pistons 3 are of diameters corresponding to the diameter of the associated compression chambers 21. In this way the compressor 1 is tailored to deliver a fluid at a certain output pressure at the outlet 13 of FIG. 1 from a fluid entering the inlet 12 of FIG. 1 at a given input pressure.
[0146] When the crankshaft 6 is driven and thereby rotated, the crankpin 5 is rotated about the rotation axis RA whereby the pistons 3 are driven in and out of the associated compression chamber 21 to compress a fluid therein. As is more clearly seen in FIG. 6, the driving in and out of the pistons 3 is achieved by the sliding shoes 4 engaging with crankpin bearings 51 mounted on the crankpin 5 and the holding rings 42 enclosing a circumference of a holding ring bearing 44 on the crankpin 5. As the crankpin 5 then rotates about the rotational axis RA, dependent on its relative position to the pistons, it either pushes the pistons 3 into the associated compression chamber by means of the sliding shoes 4, which engage with the crankpin bearings 51 and which are connected to the pistons 3 via connecting shafts 43, or pulls the pistons 3 out of the associated compression chambers 21 by means of the separate holding rings 42, which are attached to an associated sliding shoe 4 and secured to the crankpin 5 by enclosing a circumference of the crankpin 5 and the holding ring bearing 44 mounted on the crankpin 5. It can also be seen how the compression chambers 21 of the cylinders 2a, 2b, 2c are connected through non-return valves 72 to the compression chamber of the directly following cylinder. The respective chambers are connected through one non-return valve 72 for preventing flow of fluid from the compression chamber 21 of the given cylinder 2a, 2b, 2c to the compression chamber of the directly preceding cylinder. In the shown embodiment, the non-return valves 72 are located in cylindrical valve pipes 7 which comprise a pipe volume for fluid to flow through either side of the non-return valve 72. Thereby, in the embodiment shown, a fluid may enter the compression chamber 21 of the first cylinder 2a where it is compressed by the associated piston 3, and, then flows through the flow channel 28 and through the non-return valve 72 in the valve pipe 7 and into the compression chamber 21 of the second cylinder 2b where the fluid is further compressed by the associated piston 3 and flows through the next flow channel 28 and through the non-return valve 72 in the valve pipe 7 into the compression chamber 21 of the third cylinder 2c, where the fluid is even further compressed by the associated piston 3 and flows through the outlet 13 of the compressor 1. The spherical inlet ends 73 and outlet ends 74 of the valve pipes each comprise a sealing element and are press fit into the cylinder housings 22 of the cylinders 2a, 2b, 2c.
[0147] The compressor and its components are configured such that in operation, the pistons 3 move substantially only in the radial direction of the compressor 1 and in an axial direction of the respective piston 3 in the compression chambers 21.
[0148] In FIG. 4, it can also be seen that the separate annular holding rings 42 enclose a circumference of a holding ring bearing 44 mounted on the crankpin 5. The holding rings 42 are attached to the associated sliding shoes 4 via a bolt 16 that extends through the sliding shoe 4 (best seen in FIG. 7) and into the bolt hole 45 of the associated holding ring 42. For demonstration purposes, the rotation axis RA is shown in FIG. 4 and FIG. 6, whereby it can be seen that the crankpin 5 is positioned with a distance of 0.3 crankpin radii from the periphery of the crankpin 5 to the rotation axis RA. Furthermore, it can be seen that cylinders 2a, 2b, 2c comprise rod seals 24 for sealing against their associated piston. At standstill and in operation of the compressor, the associated piston 3 each cylinder 2a, 2b, 2c substantially only contacts the associated rod seal 24 of each cylinder. The pistons 3 also do not comprise any seal, such as for example a piston ring or a piston seal attached to and/or mounted on the piston 3.
[0149] Turning to FIG. 5 which shows a partially exploded view of the compressor 1, the manner in which the compressor 1 may be assembled and disassembled, and how components may be swapped out or replaced becomes apparent. The valve pipes 7 comprise a first and second valve pipe part 7a, 7b which can be disassembled from each other as shown. The valve pipe parts 7a,7b are attached to each other via a thread, where the non-return valve 72 is seated and threaded into the first valve pipe part 7a. The crankshaft bearings 62 for supporting the crankshaft 6 in the compressor housing 11 are seen positioned on shaft 61 of the crankshaft 6. As can also be seen, the cylinder housings 22 comprising the associated compression chamber 21 of the given cylinder 2a, 2b, 2c is detachable from and attachable to the compressor 1, more specifically from a cylinder base 27.
[0150] FIG. 6 shows an enlarged detail view of the crankpin, piston, and sliding shoe assembly. Each sliding shoe 4 is rotatably attached to an associated piston 3 via a connecting shaft 43 extending through the bottom end of the associated piston 3 and two portions of the associated sliding shoe 4. Each piston 3 comprises a plain bearing 46 positioned in the bottom end of the piston 3 for supporting the associated connecting shaft. Each piston 3 has a length “L” extending in the radial direction from a top surface of a top end to a bottom surface of a bottom end of the piston. The sliding shoes 4 are made of bronze, whereby the sliding shoe 4 itself may constitute a plain bearing for supporting the associated connecting shaft 46. The connecting shafts 43 extend in the axial direction and are secured to the associated piston 3 and sliding shoe 4 through two circlips 45 positioned at in the axial direction opposite ends of the connecting shaft 43. Two guide elements 33 are also attached to in the axial direction opposite ends of the connecting shaft 43 and secured to the connecting shaft by the circlips 45. A distance D from the center axis CA (FIG. 6) of the crankpin 5 to the rotational axis RA is about 1 crankpin radii. Two crankpin bearings 51 for engaging with the sliding shoes 4 are mounted on the crankpin 5.
[0151] As is best seen in FIG. 7, the sliding shoes 4 comprise a sliding surface 41 which is shaped form-fittingly to the crankpin bearings 51 for engaging with the crankpin bearings 51. The sliding surface 41 further has an opening 47 for receiving the holding rings 42 which are secured therein by a bolt 16 extending through the associated sliding shoe 4 and into bolt hole 48.
[0152] FIG. 8 shows an alternative embodiment of the cooling pipes 26 and cooling jacket 71. In this embodiment some of the cooling pipes 26 which are connected to the cooling channels (not shown) in the cylinders 2a, 2b, 2c connect to the cooling jackets 71 and enter into the cooling jacket 71 such that the valve pipes 7 and the fluid therein can be cooled. In this way the cooling jackets 71 form a part of the cooling circuit for the cylinders 2a, 2b, 2c, whereby both the valve pipes and the cylinders 2a, 2b, 2c can be cooled.
[0153] In the shown embodiment, the compressor housing 11, cylinder housing 22, valve pipes 7, cooling jacket 71, cooling pipes 26, and shield plate 17 are made of aluminium. The cylinder base 27, connecting shafts 43, crankpin 5, crankshaft 6, and clamp mechanism 63 are made of steel, with the pistons 3 being made of steel with an aluminium core. The sliding shoes 4 are made of bronze, with the holding rings 42 and guide elements 45 being made of a combination of bronze and steel.
[0154] Turning now to FIGS. 9 and 10, an embodiment of the multi-stage compressor 1 further comprising three supply compressors 8 for supplying compressed fluid at a pressure above atmospheric pressure to the compression chamber 21 of the first cylinder 2a via inlet 12 is shown. Identical or similar components have been giving the same references signs as in FIGS. 1 to 8. The supply compressors 8, positioned within an outer periphery of the multi-stage compressor 1, and the pistons 3 are driven by one and the same crankshaft 6 and crankpin 5. As the crank pin 5 rotates it actuates the supply compressor arm 81 which in turn actuates a spring loaded piston assembly 82 inside the supply compressor 8, whereby fluid is compressed to about 8 bar and out of the outlet 83 and into the inlet of the compressor 1 and the compression chamber 21 of the first cylinder 2a through respective supply pipes (not shown). The multi-stage compressor 1 then compresses this fluid as described in the above. The supply compressors 8 positioned circumferentially around the crankshaft 6 and crankpin 5 and partly inside the multi-stage compressor housing 2 operate in parallel. Additionally or alternatively, one or more supply compressor 8 may be positioned outside of the multi-stage compressor housing 2 circumferentially around the one and same crankshaft 6, 61 extending externally out of the compressor housing 2. Each of the one or more supply compressors may here potentially be driven by one and the same second crankpin. An enlarged cross-section through a supply compressor 8 is shown in FIG. 11
[0155] In the examples shown in FIGS. 1 to 11, the movement of the pistons 3 is guided by the guide grooves 15 and the guide elements 3 attached to the pistons 4 configured such that, in operation and at standstill, the associated pistons 3 do not touch an inner wall of the associated compression chamber 21 and such that, in operation, the pistons 3 only or substantially only move in the radial direction of the compressor 1. The movement of the pistons 3 may however be guided in other ways such as for example shown in FIGS. 12 to 14.
[0156] FIG. 12 shows a piston 3 and a guide element 33 comprising two linear bearings 9 in the form of slide bushings each sliding along a journal 91 in the form of a shaft. The journal 91 can be attached in or to the multi-stage compressor housing 2.
[0157] Additionally or alternatively, the multi-stage compressor 1 may comprise a number of bushing guide bars 92 per piston 3 as seen in FIG. 13, in this case three, configured for guiding the movement of the associated piston 3. The bushing guide bars 92 can be positioned and attached in the cylinder housing 22 and the compression chamber 21, to form an innermost surface of the compression chamber 21 facing the associated piston 3 and potentially providing a surface for the piston 3 to slide against. The bushing guide bars 92 extend parallel to the associated piston 3 and the movement direction of the piston 3.
[0158] Additionally or alternatively, as shown in FIG. 13 the multi-stage compressor 1 may a number of guide rollers 93, six in this shown case, configured for guiding the movement of the associated piston 3. The guide rollers 93 are positioned and attached in the multi-stage compressor housing 2 and the cylinder housing 2 to such that they can rollingly guide the movement of the associated piston 3. The guide rollers 93 are positioned along the axial direction of the associated piston 3 and around the circumference of the associated piston 3.
[0159] The multi-stage compressor may further form part of a system comprising a gas filter, a fluid filter, a cooling device such as a cryocooler, a cooling fluid tank, a power supply, a power generator, a drive unit for driving the multi-stage compressor, a compressed fluid tank, wherein, in the given case, the multi-stage compressor is connected the compressed fluid tank for supplying compressed fluid to the compressed fluid tank. The power generator may supply power to a given application such as the drive unit for driving the multi-stage compressor and other external applications. The power generator may be driven by a sustainable energy source such as solar, wind, hydro, and/or surplus energy, or the like. The system may furthermore comprise a container in which one or more of the components of the system are placed. The power generator for example may be a compressed air driven power generator driven by compressed air from the compressed fluid or air tank supplied by the multi-stage compressor and/or may be driven directly from the multi-stage compressor when power for other external applications are needed.
LIST OF REFERENCE NUMERALS
[0160] 1 Multi-stage compressor [0161] 11 Compressor housing [0162] 12 Inlet [0163] 13 Outlet [0164] 14 Cooling pipes [0165] 15 Guide groove [0166] 16 Bolt [0167] 17 Shield plate [0168] 2a, 2b, 2c Cylinder [0169] 21 Compression chamber [0170] 22 Cylinder housing [0171] 24 Rod seal [0172] 25 Cooling channel [0173] 26 Cooling pipe [0174] 27 Cylinder base [0175] 28 Flow channel [0176] 3 Piston [0177] 31 Piston top end [0178] 32 Piston bottom end [0179] 33 Guide element [0180] 4 Sliding shoe [0181] 41 Sliding surface [0182] 42 Holding ring [0183] 43 Connecting shaft [0184] 44 Holding ring bearing [0185] 45 Circlip [0186] 46 Bearing [0187] 47 Opening [0188] 48 Bolt hole [0189] 5 Crankpin [0190] 51 Crankpin bearing [0191] 6 Crankshaft [0192] 61 Separate shaft [0193] 62 Crankshaft bearing [0194] 63 Clamp mechanism [0195] 7 Valve pipe [0196] 7a First valve pipe part [0197] 7b Second valve pipe part [0198] 71 Cooling jacket [0199] 72 Non-return valve [0200] 73 Valve pipe inlet end [0201] 74 Valve pipe outlet end [0202] 8 Supply compressor [0203] 81 Actuator arm of supply compressor [0204] 82 Piston assembly of supply compressor [0205] 83 Outlet of supply compressor [0206] 9 Linear bearing [0207] 91 Journal [0208] 92 Bushing guide bar [0209] 93 Guide rollers [0210] RA Rotation axis [0211] CA Center axis of crankpin [0212] D Distance from crankpin to rotation axis [0213] d Piston diameter [0214] L Piston length
